Conventional static mixers and more recent dynamic mixers for mixing highly viscous pastes containing two components, such as dental impression compounds, are found respectively in U.S. Pat. Nos. 3,635,444, 4,014,463, 4,183,682, 4,771,919, 5,033,650, 5,080,262, etc., and 5,249,862, 5,286,105, 6,244,740, 6,532,992, 6,540,395, etc. The device, whether of the static or dynamic type, commonly comprises a cylindrical chamber enclosing a static or rotary mixer element, two inlets adapted for connection to the two components to be mixed, and a discharge opening for the mixed paste outlet. Usually, in order to match the structure positioning of the outlets of the paste component source device (such as a component dispenser), the two inlets of the mixer are located on opposite sides of the mixer shaft, separated by some distance. This separation has the effect that the two components do not reach the tubular mixing chamber simultaneously, if they travel directly, thus making it difficult to obtain a uniformly mixed result at the beginning of the discharge.
This problem has been solved in this invention by adding a dynamic premixing chamber containing a rotating shaft, attached to which are several radially directed wings. On each wing are several posts extruded towards to the inlet, outlet, or both sides of the housing, parallel to the axis of the rotating shaft. The structure of this premixing chamber, which is located between the tubular mixing chamber and the inlets are so arranged that the catalyst component will arrive to the mixing area essentially simultaneously with the impression base component. Hence the paste components from the inlet end are effectively combined in the premixing chamber before flowing into the tubular mixing chamber, already having close to the desired proportions as they first enter. The further mixing in the tubular mixing chamber produces a discharge which is uniform and of the desired proportions from the very beginning.